Patent Literature 1 describes a nitride semiconductor laser. This nitride semiconductor laser is produced on a primary surface of a gallium nitride substrate. The primary surface of the gallium nitride substrate is inclined at an angle of not less than 13 degrees and not more than 90 degrees from a (0001) plane of gallium nitride. This reduces compositional separation in an active layer of the nitride semiconductor laser.
Patent Literature 2 describes a semiconductor substrate of wurtzite-type gallium nitride. The primary surface of this semiconductor substrate is inclined at an angle of not less than 45 degrees and not more than 65 degrees from a (0001) plane to the <10-10> direction.
Patent Literature 3 describes a Schottky diode, a pn junction diode, and an MIS type transistor. These semiconductor devices are produced on a gallium nitride free-standing substrate. The primary surface of the gallium nitride free-standing substrate is inclined at an angle in the range of not more than +5 degrees and not less than −5 degrees from a (0001) plane.
Patent Literature 4 describes a Schottky diode, a pn junction diode, and an MIS type transistor. For example, it shows a relation between composite off-angle and effective carrier concentration.
Non Patent Literature 1 describes pin diodes. The pin diodes have epitaxial layers grown on a GaN free-standing substrate. The forward turn-on voltage is about 5 volts at the temperature of 300. Celsius degrees. A thick film used as the GaN free-standing substrate is grown on an Al2O3 substrate by a hydride vapor phase epitaxial (HVPE) method. This thick film is separated from the Al2O3 substrate by irradiation with a laser beam to produce the GaN free-standing substrate. On this GaN free-standing substrate, an undoped nitride semiconductor film is grown in the thickness of 3 micrometers by the metal-organic vapor phase epitaxial method. Next, an Mg-doped nitride semiconductor film is grown in the thickness of 0.3 micrometers on this undoped nitride semiconductor film. The GaN free-standing substrate, undoped nitride semiconductor film, and Mg-doped nitride semiconductor film constitute a pin structure.
Non Patent Literature 2 describes characteristics of nitride semiconductor pin junctions. First, a GaN film is formed in the thickness of 2 micrometers on a c-plane sapphire substrate by the metal-organic vapor phase epitaxial process using a SiO2 mask for LEO regrowth. A pattern of the mask is stripes with apertures of 5 micrometers at intervals of 45 micrometers. In LEO growth, a nitride semiconductor grows perpendicularly to the apertures of the mask and overgrows horizontally on the mask. The height of the grown nitride semiconductor and the length of overgrowth each are about 8 micrometers. A pn junction diode is formed on this LEO nitride semiconductor part. This pn junction diode includes an undoped n-type GaN film in the thickness of 1 micrometer, and an Mg-doped p-type GaN film in the thickness of 0.5 micrometers grown thereon. The size of the pn junction diode is 2 micrometers×20 micrometers.